Exemplary embodiments of the invention generally relate to a light emitting diode (“LED”) circuit and, more particularly, to a pulse width modulation (“PWM”) dimming circuit for LED, and more particularly.
A high power LED lamp has such advantages as high luminous efficiency, long life, and environmental protection when compared to incandescent and/or fluorescent lighting. It is believed that using LED instead of incandescent, fluorescent, and other traditional lighting will be a new trend in the coming years. LED has simplicity of driving and controlling, and illumination intensity is easy to be adjusted flexibly. LED dimming modes usually comprise DC dimming, PWM dimming and other dimming. Compared with DC dimming, PWM dimming has advantages of a constant lighting color, and good stability at low brightness.
Typically, a constant-current LED driver with loop compensation methods as a current closed-loop has slow current loop dynamic response. It is difficult for the output current to fast-track to PWM dimming signal. Thus LED lamp current can not reach the desired chopping regulation with the variation PWM signal duty cycle.